JLM Audio LA500 Opto Compressor

Projects > JLM Audio LA500 Opto Compressor

The LA500 is JLM’s take on an LA2A/LA3A-type optical compressor for the API 500-series format. Instead of cloning the original design, Joe Malone and co. have reworked the original circuit to improve signal to noise ratio and add additional control features. These include new side-chain filtering options and compression ratios. The circuit features the “JLM Sound” throughout, with their JLM99v discreet opamp and JLM111DC output transformer. JLM currently offers complete kits with everything needed to complete the compressor.


  • Electronically balanced input
  • JLM1111DC output transformer
  • JLM99v Discrete Opamp
  • 3:1, 5:1, and 10:1 compression ratios
  • “FLAT,” 100Hz, and 200Hz sidechain high pass filters
  • Mix bus output for Radial Workhorse rack
  • Same compression circuitry as LA2A/LA3A

Price: $399 AUD for full kit; $695 AUD assembled

Purchasing and more info: Available from the JLM Audio store.